Abstract

We investigated the S-doping-driven phase transition from antiferromagnetic to superconducting in single crystals. The partial substitution of Te by S suppresses antiferromagnetism in Fe-square lattice. Superconductivity is induced by oxygen annealing for only in which the long-range magnetic ordering is suppressed. To realize superconductivity in , both S concentration enough to suppress antiferromagnetism and oxygen annealing are required. Anisotropy of superconductivity in oxygen-annealed was estimated to be 1.17.